Professor jobs are nearly impossible to find now; most colleges are just hiring adjuncts, who sometimes work for subminimum wage. A PhD program is a lot of work and commitment if you're doing it without a clear goal, or if you're doing it because of the concept of "reaching your potential" (which I think is a harmful idea that leads a lot of people to make choices based on perceived prestige and not based on what they actually find fulfilling).
If you're not enjoying your current work, it does sound like a change is in order, though. There are a lot of books about how to find fulfilling work (the most popular one seems to be What Color Is Your Parachute); have you checked out any of them?
